(1) Field of the Invention:
This invention relates to a magnetic treater useful in magnetically achieving improvements in the quality of water, the clarification of water, and improvements in the quality of ready-mixed concrete or the like.
(2) Description of the Prior Art:
Red rust in water supply facilities such as piping and water storage tanks, so-called transferred rust brought in from the outside, and similar rust may be mixed even in the drinking water of a water works. Where the rust so mixed is in the form of minute particles of red rust in particular, the rust particles do not settle readily but remain in a suspended state in the water. Water which contains such red rust particles in a suspended state is called "red water", because it has a red color due to the inclusion of the particles. Red water is not good for drinking. Its clarification has therefore been attempted, for example, by using chemical methods, mechanical methods such as filtration, or biological methods.
However it is difficult in fact to use a chemical method because the thus-treated water may pose a potential danger to human beings, animals or plants. A mechanical method results in a higher equipment investment as the quantity of water to be treated increases. Accordingly, these methods have not been used in practice for actual water supply facilities. On the other hand, no feasible biological method for purifying water has been established yet and it is therefore not expected to be adopted at this stage. Under the circumstances, there is high interest these days in the exposure of water to a magnetic field for its treatment, namely, in magnetic treatment.
Magnetically-treated water is known to be effective, for example, in preventing the occurrence of red rust in drinking water or on the inner wall of piping and also removing it therefrom, promoting the growth of plants, promoting the settling of suspended solid particles, improving the strength of concrete and improving the fuel consumption of liquid fuel. A variety of apparatus have been developed for performing such magnetic treatments.
One such apparatus which may be mentioned is the water treater disclosed in Japanese Patent Laid-Open No. 154188/1984. The water treater has the following construction. Within a cylindrical space defined by inner and outer jackets made of a non-magnetic material, a plurality of annular permanent magnets magnetized in opposite poles at the inner and outer peripheral walls thereof respectively are stored via collars made of a non-magnetic material with one of the poles of each magnet being located adjacent to the opposite pole of the next magnet. A central member made of a ferromagnetic material and having an outer diameter smaller than the inner diameter of the inner jacket is inserted centrally through the inner jacket, whereby an inner flow passage is defined between the central member and inner jacket. An outer tube made of a ferromagnetic material and having an inner diameter greater than the outer diameter of the outer jacket is coaxially applied over the outer jacket so that an outer flow passage is defined between the outer tube and outer jacket. Water to be treated is caused to flow through the inner and outer flow passages.
The water treater is described to have such effects that owing to the above construction, lines of magnetic flux produced from each of the annular permanent magnets are allowed to extend across the inner and outer flow passages so as to expose the water, which is flowing through the inner and outer flow passages for its treatment, to as much a magnetic field as possible.
Another known example is a drinking water treater disclosed in Japanese Patent Laid-Open No. 33290/1986. The drinking water treater has the following construction. A plurality of axially-magnetized annular permanent magnets are arranged in a contiguous relation within a hollow cylinder in such a way that they are coaxial with one another, they are in mutual contact at poles of the same type, and their central openings form a flow passage through which drinking water may be caused to flow. The drinking water treater is described to have the following advantageous effects. Owing to the construction described above, magnetic fields are compressed by one another so that the density of each magnetic flux perpendicular to the flow can take the maximum value. Since a fluid passes inside the annular permanent magnets, the magnetic flux does not spread there so that the inside serves as a space having an effective flux density throughout. As a result, the activation of the fluid can be performed effectively, thereby exhibiting a quality-improving function without growth of bacteria.
As a further example, there is a water treater in which water to be treated is caused to flow for its magnetic treatment through a cylindrical flow passage defined between an inner tube connected to one of the opposite poles of a permanent magnet and an outer tube connected to the other pole of the permanent magnet and surrounding the outer peripheral wall of the inner tube. In this water treater, the inner and outer tubes are rendered closer to each other on the side of one end of the flow passage so that a constricted part is formed. A magnetic flux of high density is produced at the constricted part, whereby water under treatment is subjected to a magnetic treatment when it passes through the constricted part.
Incidentally, it has been substantiated empirically that the flux density required for a magnetic treatment varies depending on the application field and purpose. A magnetic treatment at a flux density of from 1,000 to 1,500 gauss has been recognized to be effective for the promotion of growth of plants including fungi. On the other hand, a magnetic treatment at a flux density of at least 5,000 gauss has been found to be effective for the removal of red rust and scale.
In the first-mentioned water treater, lines of magnetic flux are produced between a permanent magnet having an inner N pole and an outer S pole and its axially-adjacent permanent magnet having an inner S pole and an outer N pole, and the lines of magnetic flux are allowed to traverse across the entire annular cross-sections of the inner and outer flow passages. The distance between the opposite poles, however, becomes longer so that the flux density is lowered. Thus, it is only possible to obtain magnetic densities as low as about 2,000 gauss even at the highest. Although the magnetic density becomes higher in general as the cross-sectional area of a flow passage decreases, this solution is accompanied by the disadvantage that it cannot provide any necessary treatment capacity.
In the second-mentioned drinking water treater, the permanent magnets are arranged in a contiguous relation with their magnetic poles of the same polarity being in contact, thereby making use of repulsive magnetic fields. Compressed opposite magnetic fields hence exist side by side but the resulting flux densities are low. The second-mentioned drinking water treater is therefore not effective for the removal of red rust and scale. The magnetic fields are also reduced in intensity due to the repulsion, thereby making the water treater unsuitable for use over a long period of time.
In the third-mentioned water treater, on the other hand, water is magnetically treated upon its passage through the constricted part. This magnetic treatment is, however, so momentary that the magnetic treatment is not believed to be applied to its full advantage. In addition, the area of the flow passage is reduced at the constricted part and the flow passage resistance becomes greater there. This has led to another problem, namely, that the water treater can hardly achieve any desired flow rate.